Fuse device



Oct. 12, 1943.

W. O. SCHULTZ FUSE DEVICE Filed June 10, 1942 3 Sheets-Sheet l INVENTOR. Mum/14 0. Jew/z 72 ATT IEIVEY.

Oct. 12, 1943. w. o. SCHULTZ FUSE DEVICE Filed June 10, 1942 3 Sheets-Sheet 2 INVENTOR. Way/m1 0. JCf/MUZ Z2 M A O/eNEY.

\a II M Oct. 12, 1943. w, o. SCHULTZ FUSE DEVICE Fild June 10, 1942 3 Sheets-Sheet 5 INVENTOR. Mum/24 0. J 0/01 72 ATT PNEK Patented Oct. 12, 1943 FUSE DEVICE William 0. Schultz, South Milwaukee, Wis., assignor to Line Material Company, South Milwaukee, Wis., a corporation of Delaware Application June 10, 1942, Serial No. 446,463

14 Claims.

This invention relates to fuse devices.

Objects of this invention are to provide a fuse device which employs a fuse tube open at both ends and which has a headed fuse link so arranged that the head of the fuse link closes one end of the fuse tube, and in which the head of the fuse link is adapted to be blown directly away from the end of the fuse tube in the event of a violent evolution of gas upon rupture of the fuse link so that the fuse tube will be vented at both ends.

Further objects are to provide an expulsion fuse device in which a fuse tube is provided which is open at both ends and in which a fuse link is positioned within the fuse tube and is provided with a head normally closing one end of the fuse tube, and in which stationary contacts are electrically connected under normal conditions by means of the fuse link, and in which provision is made for the free travel of the head of the fuse link away from the end of the fuse tube without engaging the adjacent stationary contact so that even under violent overload conditions no damage will be caused the stationary contact by the violent projection of the head of the fuse link outwardly away from the end of the fuse tube, and to pro.- vide a construction having the characteristics enumerated above in which the head of the fuse link has good and positive electrical contact with the adjacent electrically conducting portion of the fuse device.

A further specific object of this invention is to provide an expulsion fuse device in which the fuse tube is open at both ends, one end being closed by the head of the fuse link and the head of the fuse link being gripped in such a manner that under light overloads the head of the fuse link will not be blown off and the action of the fuse tube will be that of a fuse tube open at one end only to thereby assist in the speedy clearing of the circuit inside the fuse tube, the construction being such that under heavy overloads the head of the fuse link is blown from the fuse tube to thereby provide venting of the fuse tube at both ends, the device therefore having both the characteristics of an expulsion fuse tube open at one end only for light overloads and vented at both ends for heavy overloads, whereby the safe rupturing capacity of the apparatus is materially increased.

In greater detail further objects of this invention are to provide a fuse construction in which a nut is screwed on one of the open ends of the fuse tube and is provided with slightly slanting finger portions which frictionally engage the button head or other shaped head of the fuse link and cause such head to bind tightly against the end of the fuse tube under normal conditions and thus secures excellent electrical contact between the head of the fuse link and the end terminal of the fuse tube as well as with the finger portions of the nut itself, the fingers themselves either being sufficiently yielding to allow the head of the fuse link to pass outwardly from between the fingers or else the head of the fuse link being sufficiently soft to permit the head to be slightly deformed and pass outwardly from the fingers, both of these actions preferably taking place upon violent overload.

Further objects are to provide a construction in which the threaded nut provided with the fingers for engaging the head of the fuse link is employed, such construction permitting the ready renewal of the nut at minimum expense in the event any of the fingers become'corroded or severely burned.

Further objects, for another form of the invention, are to provide a construction in which resilient gripping fingers are directly carried by the terminal of the fuse tube and grip the head of the fuse link.

Further objects are to provide a construction in which the head of the fuse link and the fingers are located above the adjacent portion of the stationary contact so that upon violent overload the head of the fuse link will be projected from, and the blast of gases will occur at a point above the stationary contact, thereby avoiding damage to the stationary contact, the fuse tube being so arranged that it will drop outwardly from operative to inoperative position after the circuit has been interrupted within the fuse tube.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a side elevation showing the device in operative position.

Figure 2 is a sectional view on the line 2-2 of Figure 1.

Figure 3 is a view of the fuse tube removed from the remainder of the apparatus, such view being partly broken away and partly in section.

Figure 4 is a sectional view on the line 4-4 of Figure 2.

Figure 5 is a fragmentary sectional view showing a further form of the invention.

Figure 6 is a plan view of the structure shown in Figure 5.

Figure 7 is a fragmentary sectional view showing a further form of the invention.

Figure 8 is a plan view of the structure shown in Figure 7.

Figure 9 is a fragmentary sectional view of a further form of the invention.

Figure 10 is a sectional view on the line ill-i of Figure 9.

Referring to the drawings, it will be seen that the device comprises a pair of stationary contacts which may be carried by a suitable elongated insulator I, such insulator itself being supported in any suitable manner. The lower contact may comprise a pair of spaced hook like members 2 which are adapted to receive the trunnions 3 of a lever 4 pivotally mounted between the bifurcated ends of an arm 5 rigid with the fuse tube 8. The lever 4 is provided with a web portion 1 which may terminate in a hook portion 8 for the reception of a switch stick for replacing the fuse device after it has been refused. The web 1 extends outwardly from the trunnions 3 and prevents inadvertent detachment of the trunnions 3 from the hooks 2 until the fuse tube has rocked downward to its lowest position. Preferably a pair of annular flanges 9 are carried by the web I to assist in correctly positioning the trunnions within the hooks 2 when the device is being replaced by means of a switch stick.

The lever 4 is provided with a thumb nut It by means of which the leader ll of the fuse link is clamped. Normally the parts are in the position shown in Figure 1. Upon rupture of the fuse link the lever 4 rocks downwardly and thus lowers the fuse tube and allows it to detach itself from the upper stationary contact hereinafter described so that the fuse tube will drop outwardly and downwardly out of operative position after the circuit has been cleared within the fuse tube. V 1

The upper end of the fuse tubeis'provided with an upper terminal member l2 which is equipped with a pair of outwardly projecting contact pins I3. The contact pins are adapted to engage beneath a pair of'spring arms 14 forming a part of the upper stationary contact. These spring arms are provided with downwardly depressed portions l5 behind which the pins I! are yieldingly hooked when the device is rocked into operative position, as shown in Figure 1. These arms I4 preferably diverge at their outer ends, as shown most clearly in Figure 2, and slant upwardly, as shown in Figure 1, so as to allow the pins i3 to ride beneath the arms into locking position, as shown in Figure 1, when the fuse tube is rocked upwardly into position. The upper terminal l2 or the fuse tube is provided with an eyelet portion i6 adapted to be engaged by a switch stick when the fuse tube is rocked into operative position or when the fuse tube is rocked out of operative position.

The arms l4 may be formed of resiliently heavy spring wire and are preferably provided with coiled portions i1 adjacent their rear ends to increase the resiliency of the arms. The arms are preferably roughly U-shaped, as shown in Fig. 2, and the rear portion ll of such arms is clamped in place between the line receiving portion IQ of the upper terminal and the rear portion of a bracket 20. A convenient way of clamping the members in place is by means of a screw 2| which passes through the upper end of the insulator and may be threaded into the base of the bracket 20.

The bracket 20 extends outwardly, as shown in Figures 1 and 2, and is provided with an outer transverse portion or plate 22 which acts as a stop to limit the inward rocking motion of the fuse tube when the device is being rocked into operative position. This plate 22 is provided with upwardly opening slots 23 on opposite sides thereof within which slots the spring arms 14 are freely received. This construction prevents spreading of the spring arms and insures their correct positioning.

The fuse tube is open at both ends. At its upper end it opens through the terminal l2 and such terminal is provided with a reduced neck portion 24 whose lower portion is threaded as indicated at 25. A nut 26 is screwed on the reduced neck and is provided with a plurality of upwardly and slightly inwardly extending fingers 21. When the nut is screwed downwardly, it grips the side edges of the button head 28 of the fuse link, such fuse link being provided with the reduced fusible section 29 and the flexible leader II and extending through the fuse tube and out from the open end thereof. The downward screwing of the nut 26 forces the head 28 of the fuse link tightly against the upper face of the reduced neck 24 of the upper terminal i2 of the fuse tube and thus secures a firm electrical contact between the head of the fuse link and the upper terminal, in addition to the contact provided by the frictional engagement between the flngers 21 and the head 28.

It is to be noted that the fuse tube is normally closed at its upper end by the head of the fuse link and under light overloads it operates as a straight expulsion fuse, the upper end remaining closed. Under heavy overloads the fuse tube is vented at its upper end and the head of the fuse link is blown upwardly and away from the upper end of the fuse tube.

The fingers 21 may be resilient if desired but at all events the head 28 of the fuse link is usually made of soft metal and will deform sumciently to allow it to be projected upwardly when the internal pressure arrives at a predetermined value.

In this way the device is capable of handling large overloads without danger of bursting the fuse tube as provision has been made for the free venting of the fuse tube at both ends under heavy overloads. In this manner the fuse tube can handle larger overloads than one in which the upper end remains permanently closed.

Another point to be noted is that the head of the fuse link is projected upwardly from a point above the upper stationary contact and consequently there is no chance of damage to the upper stationary contact as no portion thereof is struck by the outwardly projected head of the fuse link nor is any part burned by the outward blast of gases.

In the event the fingers 21 should become corroded or slightly burned from continued use,-it is a simple matter to replace the nut 26 with a new .nut. This part is relatively simple and can be' 7 vention has been illustrated in which the nut 34 fingers 3| are formed may be formed from resilient material.

The fingers 3| it will be seen slant inwardly and engage the edges of the button head 28 of the fuse link.

The upper terminal 33 of the fuse tube is provided with the threaded portion 34 on which the nut is screwed and is also provided with the reduced neck portion 35 against which the button head 28 seats. This upper terminal is also provided with the manipulating eyelet portion 38.

In the form of the invention shown in Figures 7 and 8 no nut is employed. Instead the spring fingers 31 are formed by slotting a tubular spring member part way through to provide the several fingers. The outer edges of these fingers are outwardly turned as indicated at 38 to facilitate the insertion of the button head into place between the fingers. The lower end of the tubular member is spun inwardly as indicated at 39 below a shouldered portion 40 formed integrally with the upper terminal 4| of the fuse tube. The reduced neck 42 projects upwardly from the shouldered portion 40 and is adapted to have the button head 28 of the fuse link seat thereon. The button head is frictionally gripped as in the previously described forms of the invention, but it is to be noted that the fingers are carried by the upper terminal 4| of the fuse tube itself and not by the nut. In addition these fingers may be so formed that they will be substantially straight, that is to say, form substantially a cylinder when the button head is forced downwardly into place or, if desired, the fingers may have a slight inward slant after the button head has been forced into place.

In the form of the invention shown in Figures 9 and 10 spring fingers 43 are formed integral with a tubular portion 44, which tubular portion is spun inwardly beneath the shoulder 45 of the upper terminal 46 of the fuse tube. The fuse tube continues upwardly in the form of a reduced neck 41 upon which the button head 28 of the fuse link bears. The spring fingers 43 are formed by slotting the cylindrical member 44. It is to be noted that the fingers 43 are joined to the portion 44 by means of inwardly slanting portions 48. It is preferable to provide outwardly flared end portions 50 for the fingers 43. The intermediate portions of the fingers form a cylindrical structure and engage the edges of the button head 28 of the fuse link. The fingers themselves are preferably resilient but the effect of the fingers is augmented by means of a spring ring which is a split ring, as may be seen from Figure 10. In this Way increased pressure on the marginal edges of the button head 28 of the fuse link may be obtained.

It is to be understood that the spring ring 5i could be omitted if desired and also that if desired. a spring ring could be employed with the construction shown in Figures 7 and 8.

In all forms of the invention the fuse tube is mounted for drop-out action as described in connection with the first form of the invention.

It will be seen that drop-out fuse devices have been provided in which provision is made for the normal operation of the device as a straight expulsion fuse under light overloads while at the same time providing for the free venting of the fuse tube at both ends under heavy overloads.

Further it will be seen that the construction is relatively imple and does not add any material complication to the usual type of drop-out fuse device.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. In a fuse construction, stationary terminals,

a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, and a nut screwed upon the terminal of said fuse tube and having projecting fingers gripping the edges of the head of the fuse link and holding; the head in tube closed position and in contact with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overloads.

2. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, and a nut screwed on the terminal of the fuse tube and having integral fingers gripping the edges of the head of the fuse link and holding the head in tube closed position and in contact with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overloads.

3. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, and a nut screwed on the terminal of the fuse tube and having resilient fingers attached to the body of the nut and gripping the edges of the head of the fuse link and holding the head in tube closed position and in contact with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when sunlcient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overloads.

4. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse'tube and normally in contact with the terminal of the fuse tube, and a nut screwed on the terminal of the fuse tube and provided with a tubular resilient member having slotted portions providing fingers, the fingers gripping the edges of the head of the fuse link and holding the head in tube closed position and in contact with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overloads.

'5. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having a terminal at its upper end normally electrically connected to and interlocking with the upper stationary terminal, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, a nut screwed upon the terminal of the fuse tube and having projecting fingers gripping the edges of the head of the fuse link and holding the head in tube closed position and in contact with the terminal of the fuse tube, and lever mechanism normally supporting the lower end of said fuse tube and controlled by said fuse link and releasing said fuse tube for drop-out motion upon rupture of the fuse link.

6. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having a terminal at its upper end, said upper stationary terminal having a pair of arms engaging opposite sides of the upper terminal of said fuse tube and normally interlocking therewith, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, fingers supported from the terminal of the fuse tube and engaging the marginal edges of the head of the fuse link and holding the head of the fuse link in tube closed position, and a lever supporting the lower end of the fuse tube and controlled by said fuse link and releasing said fuse tube for drop-out motion upon rupture of said fuse link.

7. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having a terminal at its upper end, said upper stationary terminal having a pair of arms engaging opposite sides of the upper terminal of said fuse tube and normally interlocking therewith, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, fingers supported from the terminal of the fuse tube and engaging the marginal edges of the head of the fuse link and holding the head of the fuse link in tube closed position, and a lever supporting the lower end of the fuse tube and controlled by said fuse link and releasing said fuse tube for drop-out motion upon rupture of said fuse link, the arms of said upper stationary terminal engaging the terminal of said fuse tube at points spaced downwardly from the head of said fuse link.

8. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having a terminal at its upper end, said upper stationary terminal including a pair of spring arms having interlocking engagement on opposite sides of the terminal of said fuse tube and including rigid guiding means for said spring arms, said guiding means constituting a stop to limit the inward rocking motion of the upper end of said fuse tube, a fuse link extending through said fuse tube and electrically connecting the upper terminal of said fuse tube with said lower stationary terminal and having a head normally closing the upper end of said fuse tube, spring fingers supported from the upper terminal of said fuse tube and engaging the edges of said head and holding said head in tube closed position, and means supporting the lower end of said fuse tube and controlled by said fuse link, said means releasing said fuse tube for drop-out motion upon rupture of said fuse link.

9. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically con nected to one of the stationary terminals, the terminal of said fuse tube having a reduced neck portion, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally resting upon and closing the neck portion of the terminal of said fuse tube, and a plurality of resilient fingers supported from the terminal of said fuse tube and surrounding said neck portion and gripping the edges of the head of the fuse link and holding the head in tube closed position.

10. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, the terminal of said fuse tube having a reduced neck portion, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally resting upon and closing the neck portion of the terminal of said fuse tube, a plurality of resilient fingers supported from the terminal of said fuse tube and surrounding said neck portion and gripping the edges of the head of the fuse link and holding the head in tube closed position, and an annular spring member surrounding and bearing against said resilient fingers.

11. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head 7 normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, and a nut screwed upon the terminal of the fuse tube and having projecting fingers gripping the edge of the fuse link and holding the head in tube closed position and in contact with the terminal of the fuse tube, the gripping force of said fingers against said head maintaining said head in tube closed position upon light overloads and allowing said head to be blown from said fuse tube upon heavy overloads, whereby upon light overloads said fuse tube acts as an expulsion fuse tube and on heavy overloads said fuse tube is vented at both ends.

12. In a fuse device a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a head normally closing one end of the fuse tube, said fuse link extending from the head through the fuse tube and projecting out of the other end of the fuse tube, and means yieldingly engaging the head of the fuse link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link.

14. In a drop-out fuse device a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a head normally closing one end of the fuse tube, said fuse link extending from the head through the fuse tube and projecting out of the other end of the fuse tube, means yieldingly engaging the head of the fuse link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link, and means controlled by said fuse link for releasably holding said fuse tube in operative position.

0. SCHULTZ. 

